The background of the invention will be set forth in two parts.
1. Field of the Invention
This invention relates to microwave devices and more particularly to waveguide switches.
2. Description of the Prior Art
In microwave systems, it is often desirable to have an electromagnetic wave energy transmission line switch, such as a waveguide switch, which will conduct such energy from a first waveguide section to either a second or to a third waveguide section, or from either the second or third waveguide section to the first waveguide section.
Such switches have been available for quite some time and are generally manually operated or provided with remotely controlled (electromechanical) actuating mechanisms such as motors and rotary or linear solenoids. The waveguide switches generally include a housing incorporating a stator portion and a rotor portion in which one or more waveguide channels are provided. The housing or stator includes appropriate flange connections at the port locations. The rotor can then either be manually or remotely rotated within the stator housing and, depending on the rotor position, the various waveguides connected to the stator flange connections are linked to each other. Electrical continuity between the rotor and stator portions of the switch is generally achieved by means of quarterwave chokes providing high isolation between the rotor waveguide channels.
In most ground-based installations, the prior art waveguide switches admirably fulfill their function. However, in spacecraft applications where space and weight must be kept to an absolute minimum, presently known waveguide switches cannot perform certain necessary functions without adding weight and complexity to the system.
For example, it is necessary to provide back-up capability in the spacecraft most active devices such as traveling wave tubes and other microwave generators since the loss of even a single such device could completely ruin an important space task. Accordingly, in almost all space oriented systems, a redundency system is used whereby a failing or dead device can be bypassed and/or a backup devices switched into the system, either automatically or by ground terminal command.
Current waveguide switches are single pole double throw or transfer devices, the latter allowing each port to be alternately connected to its two adjacent ports. In order to provide the necessary switching in a redundency system, previous waveguide circuits used two separate waveguide switches. It should therefore, be quite evident that a new waveguide switch which eliminates two previously required waveguide switches in every redundency system about a spacecraft and which also enable the shortening of RF transmission lines to reduce transmission line losses, would constitute a significant advancement of the art.